The present invention relates to a projection system for the display of aerial images and more particularly, to a projection system for displaying three-dimensional video images.
Aerial image projection systems are known in the art. Such systems utilize a plurality of optical elements such as mirrors, Fresnel lens and optical filters or polarizers to project an image of an object into space. The optical elements and the object are positioned in a housing to define an optical path. Depending on the arrangement and selection of the optical elements, the projected image is visible either within the dimensions of the housing or a short distance in front of the housing. Examples of aerial projection systems include U.S. Pat. No. 5,311,357, issued May 10, 1994, U.S. Pat. No. 5,552,934, issued Sep. 3, 1996, U.S. Pat. No. 4,802,750, issued Feb. 7, 1989, and U.S. Pat. Des. No. 435,043 issued Dec. 12, 2000.
Prior art aerial projection systems are expensive because of the cost of optical components required to project the aerial image of an object. More specifically, such systems use one or more concave glass mirrors in the optical path together with one or more glass polarizers maintained in a fixed orientation with respect to a stage where an image is positioned. Unfortunately, 15-inch concave glass mirror costs well over $1,000 and polarizers cost about $850. Clearly, glass mirrors and polarizers are major contributors to the high cost of the prior art aerial projection system. Not only expensive, these mirrors and polarizers are also very heavy so adequate support must be provided. Accordingly, a heavy box-like housing is used to maintain the orientation of the optics with respect to the object. Unfortunately, transporting the housing from one location to another is difficult and expensive. What is needed is an aerial projection system that lightweight, inexpensive and easily transported from one location to another.
While prior art aerial projection systems generate visually captivating aerial images, there are a number of problems that limit use of aerial projection systems in a wide variety of applications. Accordingly, prior art aerial projection systems are typically used in museums or retail stores to display expensive items where the object being displayed can be kept safely out of the reach of the observer.
Prior art aerial projection systems typically use a three-dimensional object as the source of the image. For example, a small statue may be placed on a pedestal and brightly lighted with spotlights. The three-dimensional image of the statue is projected through a display window and viewed by observers who are positioned in front of the display window as if it were floating in air.
One problem with using an object as the source of the projected image is the difficulty and expense associated with changing the image. Thus, to maintain the viewer""s interest and to preserve the novelty of the projected image, the object must be constantly changed. This is a labor-intensive process as an attendant must open a door in the housing, remove the object, position a new object and verify that it is properly positioned on the display pedestal.
To overcome this limitation, aerial display systems have attempted to utilize a video display device instead of a physical object as the image source. Unfortunately, the video images appear together with an image of the display screen. Thus, rather than displaying a floating image, the aerial image appears to the observer as a floating video display screen thereby rendering the illusion of an image floating in air ineffective. What is needed is an aerial projection system capable of displaying video images without the video display screen being visible to the observer.
Another problem associated with the display of video images arises from the display device itself. Specifically, video monitors use a flat piece of optical quality glass behind which the image is generated. This glass tends to reflect external images that pass through the optics in the optical path. The reflected image is viewable by the observer resulting in a noticeable double aerial image. Clearly, what is needed is an aerial projection system that eliminates reflected images from the displayed aerial image.
Yet another problem with prior art display of video images arises when the object of attention moves off screen. More specifically, when an image transgresses beyond a boundary of the display, the observer immediately detects the edge condition and the illusion of a floating image is lost. Accordingly, what is needed is a method for displaying an aerial image in a manner that does not suggest that the image is generated by a video display.
Thus, a better system and method for projecting aerial images is needed. More specifically, what is needed is an aerial projection system for projecting images at video rates that is lightweight and inexpensive.
The present invention relates to an aerial projection system and method. More specifically the present invention relates to an aerial projection system having a housing for positioning low cost optical elements capable of generating a three dimensional aerial image that is projected outside the dimensions of the housing and that is visible to an observer in ambient light conditions. The system is capable of displaying three-dimensional aerial images at video display rates without reflected artifacts or visible display of the display screen. The method incorporates a set of rules to eliminate boundary transgressions and to maximize the illusion of a three dimensional aerial image.
In one preferred embodiment, the system of the present invention includes a plastic concave mirror positioned opposite in the housing. A planar plastic beam splitter is positioned in front of the concave mirror. The beam splitter is preferably oriented at a forty-five degree (45xc2x0) angle relative to the face of the mirror. To minimize glare and reflections, a polarizer is affixed closely proximate to the beam splitter. The polarizer is preferably aligned parallel to the beam splitter.
An improved high-bright liquid crystal display (HLCD) device is positioned proximate to the beam splitter such that the beam splitter projects images onto the mirror and then out through the polarizer. A computer system, coupled to the HLCD device, provides a source of images for display at video rates. The computer system may drive a single HLCD display or a plurality of displays. Novel features of the HLCD device and the method for presenting images eliminate projection of an observable boundary. Images displayed on the HLCD device comply with a set of display rules so that the observer is not presented with display incongruities that would ruin the illusion of a floating aerial image. Specifically, the rules limit the movement of displayed objects beyond the edge or boundary of the HLCD device and limit background colors that would cause the edge of the HLCD device to be come visible. Accordingly, movement of displayed objects is in accordance with selected techniques.
In another preferred embodiment, the computer system is coupled to a communication network so that an image sequence is transferred to the computer system from a remote location for display. The communication enables the observer to request additional information or to select the display of a different sequence of video.
In yet another preferred embodiment, a second display is provided proximate to the HLCD display. This second display is preferably a transparent imaging panel that acts selectively as a light valve, as a display platform for special effects or for providing the appearance of linear motion towards or away from the observer.
In yet another preferred embodiment, a third display device is provided at the portal. The third display device is also preferably a transparent imaging panel that is used as a background display device for displaying video rate images that are not projected aerial images. Thus, the observer is presented a rich and varied display environment where the background display is combined with projected images. With the three display devices, the observer is actively engaged in viewing a dynamic, realistic video event.
The present invention further includes a method for generating and displaying three-dimensional aerial images using the above described system. The method includes a set of software development tools for crafting and positioning three-dimensional images on the first and second displays so that an observer perceives three-dimensional images floating in space without detecting the boundary of the displays. The software development tools further include logic for developing a sequence of video rate aerial images.
The important advantages of the present invention will become apparent as the description that follows is read in conjunction with the accompanying drawings.